Sen. Ted Cruz (R-Texas) and Sen. Marco Rubio (R-Fla.) are clashing over how intelligence agencies should handle the phone data of private citizens.

Over the weekend, Cruz retaliated against an ad criticizing his vote for a bill that limits the government’s ability to collect and monitor private citizens’ cell phone data.

In June, Cruz voted in favor of the USA Freedom Act, a bill intended to limit government agencies’ ability to collect and store citizens’ private data. President Obama signed the bill into law just hours after Congress passed it, reigning in some of the surveillance programs established by Bush-era national security measures.

In the aftermath of 9/11, then-President Bush signed the Patriot Act, which allowed the government to collect massive amounts of data on citizens, including cell phone records, to monitor potential terror activity. In 2013, Edward Snowden leaked classified information revealing the National Security Agency’s surveillance program to journalists. The revelations spurred congressional debate over the scope of the programs authorized under the Bush administration.

On Sunday, some aspects of the National Security Agency (NSA) data collection program came to an end because of the Freedom Act, which passed the House with 388 votes and the Senate with 67 votes. Now government agencies no longer have an open invitation to look at citizens’ phone data whenever they want. Instead, agencies must submit a request to a phone company for the information that belongs to a specific phone number they already suspect as being connected to terror activity.

Rubio, who opposed the bill, has capitalized on his voting record in wake of the terrorist attacks in Paris earlier this month.

“[The Freedom Act] eventually undermines our ability to collect information and to monitor those who seek to harm the United States,” Rubio said.

“Ted Cruz voted to weaken America’s ability to identify and hunt down terrorists,” a narrator says, while footage of the Paris attacks plays on a loop.

“Call Ted Cruz,” the ad concludes. “Tell him to stop leading from behind.”

In response, Cruz’s campaign released a video on Saturday attacking Rubio for his participation in the Gang of Eight immigration reform bill in 2013. In the video, Rep. Jim Bridenstine (R-Okla.) said Rubio’s immigration reform plan “would’ve expanded the U.S. refugee resettlement program and given Obama the authority to let in even more Syrian refugees.”

The same day that the video was released, Cruz attacked Rubio before reporters during a campaign stop in Iowa.

“I imagine Sen. Rubio’s PAC is trying to respond to the criticism that is receiving that he was not willing to protect the Fourth Amendment privacy rights of law-abiding citizens, and they are attempting to do so by attacking those of us who were,” he said.

The Fourth Amendment of the Constitution protects American citizens from unreasonable search and seizure by the government. In other words, it provides that one’s possessions or correspondence won’t be collected and examined without probable cause. In May, the Second Circuit Court of Appeals ruled that the NSA’s bulk collection of data was unconstitutional.

Cruz is saying that Rubio didn’t protect the Fourth Amendment because he voted against the Freedom Act, which curtailed the constitutionally questionable aspects of the NSA’s program.

This isn’t the first time Rubio’s immigration stance has been attacked in the ongoing immigration fight between the two Republican senators vying for the White House. Courageous Conservatives PAC sponsored a mid-November ad hitting on Rubio’s immigration reform bill while lauding Cruz’s opposition to it.

“Marco Rubio betrayed our trust, failed us, and he’s done nothing since coming to Washington but push for amnesty,” the narrator says at the end of the ad.

The rift between the two candidates on national security has escalated in recent weeks, and represents a larger split within the Republican Party. Rubio’s decision to attack the Freedom Act could alienate him from conservative and independent voters with libertarian sympathies, who are more wary of government in general and government surveillance programs in particular.

However, in the wake of the Paris attacks, the conversation surrounding the government surveillance has shifted, and several Republicans have spoken out in favor of restoring the NSA’s metadata collection program.

Rubio and Cruz will likely get a chance to confront one another face to face over national security in the upcoming Republican primary debate, which will be sponsored by CNN on December 15.

Bre Payton is a staff writer at The Federalist. Follow her on Twitter.

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